Description: The aims of this Core are to improve diagnostic criteria and measurement of need for mental health services particularly among special populations, in this case the elderly and ethnic and racial minorities; to determine how treatment and care can be made more cost effective and culturally appropriate; and to increase the relevance of mental health services measurement for clinical and policy making decision making. The Core seeks to achieve these aims by proposing three multi-year studies relating to diagnostic criteria and needs assessment, and a fourth that addresses the cost of effective care. The first study reconceptualizes mental disorders in terms of harmful dysfunction. Initial examination of existing data sources reveal that this is a useful concept in that assignment of patients to symptomatic or diagnostic categories it is not over-inclusive, better meets assessment needs of special populations and community-based populations, and is more useful for planning. The investigators will further examine its utility by reanalyzing ECA and National Comorbidity Survey data. The second proposes to develop an instrument to measure depression among the elderly, and then to test interventions using the instrument. The third study expands to children in Puerto Rico work done with adults on the determination of how cultural -psychiatric syndromes are assessed and which pathways lead to provision of services. The fourth study proposes to use the cost methodologies developed for current studies and expand their development and dissemination in mental health research.